Algerian Journal of Engineering and Technology (AJET)
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Synthesis and characterization of polymeric inclusion membrane containing Dibenzo-18-Crown- 6 as carrier of uranium ions
Get PDFLiquid radioactive waste generated during nuclear operations has a variable chemical and radioactive composition. Uranium is among the most dangerous radionuclide present in this liquid waste due to its chemical toxicity and radioactivity, hence the need for its removal from aqueous solutions. Several techniques have been used for this purpose.Polymer inclusion membranes, also called third-generation membranes, are used for this treatment; they have the advantage of being selective because they incorporate specific extractants into their structure. In this study, cellulose triacetate (CTA)-based polymer inclusion membranes containing 2-nitrophenyl octyl ether (2-NPOE) as a plasticizer and dibenzo-18-crown-6 (DB18C6) as a carrier, in different amounts (0.04, 0.07, and 0.1 g), were synthesized. The physicochemical and structural properties of the synthesized membranes were determined.Characterization results from Fourier transform infrared (FTIR) spectroscopy and scanning electron microscopy (SEM) show that DB18C6 is properly incorporated into the polymer matrix of the membrane. Characteristic bands of the polymer, plasticizer, and carrier are present in the FTIR spectra of the CTA-2NPOE-DB18C6 membrane. This result is confirmed by SEM analysis, which reveals that the polymer pores of the membrane are filled by plasticizer and carrier molecules. The performance of the prepared membranes with respect to uranium was studied by determining the amount of uranium fixed to the membrane. The results showed that 0.07 g of DB18C6 is sufficient for maximum uranium binding (92%) to the membrane, compared to membranes containing 0.04 g and 0.1 g of the DB18C6
Steady-State thermal-hydraulic and neutronic analysis of the NUR research reactor current configuration
Get PDFMaintaining adherence to safety standards and limitations throughout a nuclear reactor's operational life is crucial to preventing incidents and accidents that could have detrimental effects on workers, the general public, and the environment. The integrity of the fuel, and specifically the first safety barrier (the fuel cladding), must be maintained in order to reduce the likelihood of an accident. Compliance with these limits ensures that even at the hottest point of the reactor core, the safety limits cannot be exceeded. This study provides a thermal-hydraulic and neutronic analysis of the currentconfiguration of the NUR research reactor under steady-state conditions. Its primary aim is to ensure that all the critical thermal-hydraulic parameters uphold margins below the safety limits. The neutronics calculations were performed using OpenMC code validated by the obtained results of WINS/CITVAP ,power density distribution and Power Peaking Factors (PPFs) were calculated. The PPFs for each channel in the core are obtained, and the hot one is then localized. These results were injected in thermal-hydraulic model established by PARET code, in which the core was divided into two regions (two parallel fuel platesand their associated cooling channels). The first region represents the hottest channel in the core, and the second one, the remainder part named the average channel. This model provides the evolution of the fuel, coolant, and cladding temperatures in the hot channel. The temperature profiles generated were compared to those of the asymptotic model of a previous work and those acquired by the TERMIC.1H code in order to validate the PARET model for the reactor core. Consequently, under steady-state conditions, the clad's maximum temperature remained well below the safety limit. The most significant obtained result is that the NUR research reactor can safely operate at a nominal power while staying within the thermal safety limitations
Integrated Experience Feedback-Knowledge Management Approach for Enhanced Safety of a Research Reactor
Get PDFIn the nuclear field, safety is a fundamental requirement, driven by the need to protect workers, the public, and the environment from the effects of ionizing radiation. Nuclear safety increasingly relies on organizations' ability to manage their knowledge effectively in a context marked by rapid technological changes, skills renewal constraints, and growing operational complexity. Two complementary approaches play a strategic role in sustainably strengthening nuclear safety: Experience Feedback (EF) and Knowledge Management (KM). This article is based on a qualitative analysis of IAEA safety standards and technical documents, combined with the author's professional experience. The proposed integrated EF-KM cycle is derived from this analysis and is presented as a conceptual framework for implementation. The synergy between EF and KM contributes to the overall performance of safety systems by preventing error repetition, preserving tacit knowledge, and fostering a proactive safety culture. This article constitutes a direct advocacy for research reactor operating organizations to formally establish and integrate robust EF and KM programs as a strategic necessity, rather than treating them as optional initiatives. The paper also discusses implementation challenges and provides global success cases from EDF, WANO, and Bruce Power to ground the theoretical framework in practical reality. A practical example involving a transient iodine release is used to illustrate the operational benefits
Influence of hydrogen reduction temperature in a fluidized bed on AUC derived UO₂ powder properties
Get PDFThe production of uranium dioxide (UO₂) powders by calcination–reduction of ammonium uranyl carbonate (AUC, (NH₄)₄UO₂(CO₃)₃) is an important step in the UO₂ fuel pellet fabrication process. The nature and quality of the resulting UO₂ depend closely on the initial characteristics of AUC as well as on the applied thermal treatment conditions. The UO₂ powders obtained must meet specific requirements, particularly those related to specific surface area (4.5–7 m²/g) and particle size distribution. The objective of this work is to analyze the effect of the hydrogen reduction temperature on the properties of AUC-derived UO₂ powders using a fluidized-bed furnace. In this study, the reduction temperature of AUC was varied from 400 to 550 °C, and the resulting UO₂ powders were characterized. The O/U ratio, specific surface area, and particle size distribution of the UO₂ powders were determined respectively by spectrophotometry, nitrogen adsorption–desorption (BET method), and laser granulometry. During tests on stabilization of the AUC powder bed, it was observed that the minimum fluidization flow rate ranged between 20 and 30 L/min. Within this range, a proportional relationship was observed between the pressure drop and the fluidization velocity. Beyond 30 L/min, the fluidized bed became stable. As the reduction temperature increased from 400 to 550 °C, the specific surface area decreased from 10.2 to about 7 m²/g (±0.2 m²/g). However, the particle size distribution of the UO₂ powders varied only slightly with temperature. A reduction temperature of 550 °C under hydrogen in a fluidized bed was selected as the optimal condition for the conversion of AUC into UO₂ powder exhibiting good sintering properties for nuclear fuel pellet production (7 m²/g)
Performance Evaluation and Optimization of Split-unit Maize Dehusking and Threshing Machine
Get PDFManual maize dehusking is laborious, time consuming and non-economical. The dehusking unit of the existing maize dehusker cum thresher are not separated. This is responsible for large quantity of impurities in the threshed grains thereby leading to low input capacity per kilowatt hour. A split-unit maize dehusking and threshing machine was developed in an attempt to address this challenge without evaluating its performance. Hence, the focus of this research was to study the effects of moisture content (MC) and machine speed (MS) on the performance of maize dehusking and threshing machine using response surface methodology. The response variables were dehusking efficiency (DE), threshing efficiency (TE), cleaning efficiency (CE), throughput capacity (TC), mechanical damage index (MDI), total grain loss (TGL) and input capacity per kilowatt-hour (ICK). A randomized 3x3 factorial i-optimal experimental design was employed. Mathematical models relating the input variables to the performance indices were developed. The predicted optimum values obtained were validated using the values obtained from the experiment. The machine speed was discovered to have the greater effect on the response variables than moisture content for the experiments carried out. The optimization process revealed that the optimal values for the performance indices of the maize machine were obtained at the moisture content (17.09 % wet basis) and machine speed (1500 rpm). The optimum values for DE, TE, CE, TC, MDI, TGL and ICK were 98.51 %, 99.80 %, 98.9%, 315.80 kg/h, 0.51 %, 9.1 % and 651.38 kg/kWh respectively. The difference between the predicted values and the experimental values was insignificant with minor deviation for all response variables investigated. The mathematical models developed for the DE, TE, CE, TC, MDI, TGL and ICK adequately represent the relationship among variables of the study
Impact of Nanoparticles on Clay Sedimentation in Liquids
Get PDFClay sedimentation in colloids is a natural phenomenon that can be accelerated or retarded with additives. This is important in drilling operations where clay suspension in drilling muds is desired for effective functionality. Current studies have indicated that nanoparticles can improve rheological properties of drilling fluids but not much is known about their impact on clay sedimentation. Hence, this work investigates the effect of eight kinds of nanoparticles on clay sedimentation in the absence and presence of crude oil. A small fraction of these nanoparticles were dispersed in distilled water, brine of 30g/l salinity, ethanol and diesel containing clays, and the volume of settled particles under gravity were plotted against time. Linear graphs and parabolic shaped graphs within the short periods of observation indicate slow and accelerated sedimentations respectively. Results show that aluminum oxide and zinc oxide nanoparticles speed up clay sedimentation while nanoparticles of magnesium, zirconium, nickel, iron, tin and silicon oxides retard clay sedimentation rate in liquids, rendering these six kinds of nanoparticles potential clay stabilizers. In the absence of nanoparticles it was observed that clay sedimentation in water is slower than in ethanol and diesel and the presence of crude oil further slows down sedimentation. But in the presence of nanoparticles, the effect of crude oil on clay sedimentation is inconclusive, necessitating further studies
Devulcanizing Algerian End-of-life Tire Rubber for Rubber Sustainability and Rubber Product Circular Economy, in Algeria
Get PDFManaging end-of-life tires (ELTs) remains a persistent global challenge for the transportation sector. Once discarded due to wear or irreparable damage, scrap tires pose severe environmental and health hazards. Although various disposal methods have been developed including landfilling, incineration, and crumb rubber production most are unsustainable and environmentally harmful. The vulcanization process, which transforms raw rubber into durable tire material, significantly hinders recycling efforts. However, recent technological advances offer promising solutions. In Algeria, over 6.2 million registered vehicles in 2020 generate more than six million scrap tires annually, with numbers expected to grow rapidly due to increasing vehicle ownership, shorter tire lifespans, and expanding electric and heavy-vehicle fleets. Without proper management, this waste will accumulate dramatically, exacerbating environmental degradation. Windsor Industrial Development Laboratory has developed an innovative devulcanization technology under the EcoCa™ brand, capable of reversing the vulcanization process effectively transforming used tire rubber back into a reusable form. This breakthrough enables the manufacturing of high-quality engineered rubber products. As a first application, the laboratory has successfully produced and tested passenger vehicle parking blocks made entirely from devulcanized rubber. The proposed four-step approach includes: i. Rubber recovery from scrap tires, ii. Devulcanization of the recovered rybber, iii. Compounding the devulcanized rubber, and iv. Manufacturing green products from recycled rubber. This technology offers multiple benefits: addressing environmental pollution, promoting rubber sustainability and circular economy, conserving natural resources, reducing energy consumption and greenhouse gas emissions, creating jobs, and building local technical expertise in Algeria. Windsor’s laboratory seeks industrial and academic partners in Algeria to establish a sustainable local recycling chain and support zero-waste manufacturing practices in the Rubber Industry
Recovery of uranium (VI) from aqueous effluents by an NaX zeolite and NaX modified by Na2SO4
Get PDFThis work aims to develop innovative materials that promote optimal uranium recovery. It focuses on the modification of NaX zeolite by sodium sulfate (Na2SO4) by hydrothermal means, then used as an adsorbent for uranyl ions. Analytical techniques such as X-ray diffraction, Fourier transform infrared spectroscopy, nitrogen adsorption-desorption and thermal analysis were used to characterize the structural and textural properties of the synthesize and modified material. The kinetics, adsorption isotherms and desorption cycle of NaX, NaX-Na2SO4 zeolites were studied to evaluate their potential for uranium adsorption. The experimental results indicate that the uranium adsorption capacity was improved from 23 mgU/g for NaX to 35 mgU/g for NaX-Na2SO4 in the concentration range of 10-300 mg/L in U, under the optimal conditions: pH 2.0, room temperature, initial concentration of 100 mg/L in U, (S/L) ratio of 10g/L and 7g/L, and contact time of 3h and 2h respectively for NaX and NaX-Na2SO4. The kinetic study revealed that the recovery of uranyl ions follows a pseudo-second-order model and the adsorption equilibrium data fit better to the Langmuir model for both materials. Desorption using 0,5 N HNO3 solution resulted in approximately 90% recovery of uranyl ions after one treatment cycle using the modified NaX zeolite
Hydrodynamic Parameters Study of Gas-Solid Fluidized Bed Reactor: Case of AUC Conversion to UO2
Get PDFThe fluidization technique is used for gas-solid interaction processes whenever high rates of heat and mass transfer between the two constituents is required. This work aims to contribute to the understanding of the hydrodynamic parameters of gas-solid fluidized bed reactors in the case of the conversion of AUC powder (ammonium uranyl carbonate) into UO₂ powder (uranium dioxide). The study focuses on the fluidization velocity effect on the pressure drop evolution during the fluidized bed process, as function of the temperature and type of gas used (pure N₂, pure H₂, and a 50% H₂–50% N₂ mixture). The study will also present the results of the gas flow rate variation as a function of temperature, as well as the results of the pressure drop variation as a function of the fluidization velocity, taking temperature as a parameter for pure N2, pure H2 and 50% H2-50% N2 mixture. Calcination-reduction experiments were conducted, using a fluidized bed reactor to convert AUC powder into UO2. These experiments examined the influence of process parameters on particle size, specific surface area, O/U ratio and porosity of the UO2 powder produced. Using the optimized operating parameters, such as the fluidization velocity, gas flow rates, and treatment temperature of the fluidized bed reduction-calcination process, ensured the production of UO₂ powders with the required physicochemical characteristics
LQR Control of a Flexible Satellite with Movable Mass Actuation
Get PDFThis paper addresses the challenging problem of optimal control for a flexible satellite equipped with a movable mass actuator. The dynamics of the satellite system include both rigid body rotations and elastic vibrations due to flexible appendages, which are modelled using second-order differential equations. The primary control input is generated by the strategic movement of an internal mass, which simultaneously produces torques for attitude stabilization and mitigates vibrational energy in the flexible modes. To achieve a delicate balance between minimizing state deviation and control effort, An optimal Linear Quadratic Regulator (LQR) strategy is implemented and its performance is compared with that of a conventional PD controller. The stability of the closed-loop system is theoretically established using the Lyapunov theory. Numerical simulations validate the proposed approach, demonstrating its effectiveness in minimizing flexible mode excitation and maintaining satellite attitude